The present invention relates to a magnetic disk recording apparatus for performing at least one of recording signals onto at least one magnetic recording disk and reading out the signals from the magnetic recording disk.
In a prior-art magnetic disk recording apparatus as disclosed by JP-A-11-16311, a first actuator moves a support arm with respect to a magnetic recording disk, a support member holding thereon a magnetic head is connected to the first actuator through the support arm to be driven by the first actuator through the support arm, a second actuator moves the support member with respect to the support arm so that the support member is moved with respect to the magnetic recording disk by the first actuator and the second actuator, the first actuator moves the support member through the support arm by a relatively large length with respect to the magnetic recording disk, and the second actuator moves the support member by a relatively small length with respect to the magnetic recording disk.
An object of the present invention is to provide a magnetic disk recording apparatus for performing at least one of recording signals onto at least one magnetic recording disk and reading out the signals from the magnetic recording disk, in which apparatus a magnetic head is correctly positioned without an undesirable vibration thereof.
According to the invention, in a magnetic recording apparatus for performing at least one of recording signals onto at least one magnetic recording disk and reading out the signals from the magnetic recording disk, comprising, a support arm movable with respect to the magnetic recording disk, a first actuator for moving the support arm with respect to the magnetic recording disk, at least one magnetic head for performing through the magnetic head the at least one of recording the signals onto the magnetic recording disk and reading out the signals from the magnetic recording disk, a pair of support members at least one of which holds the magnetic head thereon and each of which is connected to the first actuator through the support arm to be driven by the first actuator through the support arm, and a pair of second actuators for moving respectively the support members with respect to the support arm so that the support members are respectively moved with respect to the magnetic recording disk by the first actuator and the second actuators,
the second actuators move simultaneously the support members respectively with respect to the support arm in respective directions opposite to each other.
Since the second actuators move simultaneously the support members respectively with respect to the support arm in respective directions opposite to each other, a force (for example, rotational moment) moving one of the support members cancels a force moving another one of the support members so that a vibration caused by moving simultaneously the support members respectively with respect to the support arm is not generated to keep an accuracy in positioning the magnetic head.
The magnetic disk recording apparatus may comprise a pair of the magnetic heads while each of the support members holds the magnetic head thereon as a combination of the magnetic head and the support member. When the support members with the respective magnetic heads thereon are respectively swingable with respect to the support arm, it is preferable that a moment of inertia of one of the combinations around the support arm is substantially equal to that of another of the combinations around the support arm to effectively cancel the forces. When the support arm is swingable on an rotational axis of the first actuator, it is preferable that a moment of inertia of one of the combinations around the rotational axis is substantially equal to that of another of the combinations around the rotational axis to effectively cancel the forces.
Alternatively, one of the support members may be prevented from holding the magnetic head thereon, and hold a counter weight. When the support member with the magnetic head thereon and the support member with the counter weight thereon are respectively swingable with respect to the support arm, it is preferable that a moment of inertia of a combination of the support member and the magnetic head around the support arm is substantially equal to that of a combination of the support member and the counter weight around the support arm to effectively cancel the forces. When the support arm is swingable on an rotational axis of the first actuator, it is preferable that a moment of inertia of a combination of the support member and the magnetic head on the rotational axis is substantially equal to that of a combination of the support member and the counter weight on the rotational axis to effectively cancel the forces.
It is preferable that the second actuators move simultaneously the support members respectively with respect to the support arm in the respective directions opposite to each other by respective distances, speeds and/or forces (accelerations or decelerations) substantially equal to each other.
It is preferable for keeping correctly a relationship in position and/or attitude between the support arm and each of the support members that at least a part of the support arm and at least a part of each of the support members are monolithically formed, and a flexible area is arranged between the at least a part of the support arm and the at least a part of each of the support members.
When the second actuators are expandable and contractible to move respectively the support members with respect to the support arm, the second actuators are energized in such a manner that one of the second actuators expands to move one of the support members in a first direction while another one of the second actuators contracts to move another one of the support members in a second direction, the first and second directions being opposite to each other. It is preferable for keeping correctly a relationship in position and/or attitude between the support members that the second actuators are arranged in such a manner that directions parallel to a magnetic recording disk thickness direction in which directions the support members are simultaneously bent at least partially respectively by the expandable and contractible second actuators with respect to the support arm are identical to each other when the second actuators are energized to move respectively the support members with respect to the support arm. Areas of the support members onto which the second actuators are fixed respectively may face to each other in the magnetic recording disk thickness direction. It is preferable that a flexible member connecting the support arm to each of the support members is juxtaposed with each of the second actuators in the magnetic recording disk thickness direction so that the support members are bent at least partially with respect to the support arm respectively in the directions parallel to the magnetic recording disk thickness direction by the second actuators.
The second actuators may be piezoids. When one of the second actuators has a first pair of expandable and contractible actuators to swing one of the support members around the support arm, and another one of the second actuators has a second pair of expandable and contractible actuators to swing another one of the support members around the support arm, it is preferable that the second actuators are energized in such a manner that one of the expandable and contractible actuators of the first pair expands while another one of the expandable and contractible actuators of the first pair contracts so that the one of the support members is swung in a first circumferential direction around the support arm, and one of the expandable and contractible actuators of the second pair expands while another one of the expandable and contractible actuators of the second pair contracts so that the another one of the support members is swung in a second circumferential direction around the support arm, the first and second circumferential directions being opposite to each other. It is preferable for keeping correctly the relationship in position and/or attitude between the support members that the expandable and contractible actuators are arranged in such a manner that directions in which the support members are simultaneously twisted respectively by the first pair of the expandable and contractible actuators and the second pair of the expandable and contractible actuators with respect to the support arm are identical to each other when the second actuators are energized to swing respectively the support members with respect to the support arm. It is preferable that a flexible member connecting the support arm to each of the support members is juxtaposed with each of the second actuators in the magnetic recording disk thickness direction so that the support members are twisted respectively with respect to the support arm by the expandable and contractible actuators.
It is preferable that a polar direction of the piezoid of one of the second actuators is directed away from one of the support members moved by the one of the second actuators while a polar direction of the piezoid of another one of the second actuators is directed toward another one of the support members moved by the another one of the second actuators so that the one of the second actuators expands while another one of the second actuators contracts when the second actuators are energized.
When the piezoid of each of the second actuators has a pair of first electrode adjacent to the support members in the magnetic recording disk thickness direction and second electrode distant from the support members in the magnetic recording disk thickness direction, it is preferable for easily energizing the piezoids that electric potentials applied to the second electrodes respectively are equal to each other and/or that the first electrodes are electrically grounded. It is preferable for easily energizing the piezoids that an electric potential difference to be applied to the piezoid of one of the second actuators to be activated is equal to an electric potential difference to be applied to the piezoid of another one of the second actuators to be activated.
It is preferable for effectively canceling the forces that a change in electric potential difference to be applied to the piezoid of one of the second actuators to be activated in accordance with a time proceeding is substantially equal to an electric potential difference to be applied to the piezoid of another one of the second actuators to be activated in accordance with the time proceeding so that the movements of the support members in respective directions opposite to each other are synchronized.
The support members and/or the support arm may be electrically grounded.